Valve control of fluid flow, both gases and liquids, is an old and well populated art. Numerous styles of soft check valves are known, the following are representative of the current art. Collectively, arranged chronologically, each with a short description, they provide in their entireties a useful background for understanding the new teachings to the art taught by the description of biflex film valves provided herein. Being cited, each therefore is fully incorporated herein as a pertinent teaching.
Jaron, U.S. Pat. No. 4,966,197 (1990), “One-way Valve” is a form of flattened duckbill design where two resilient chamber walls define a tortuous pathway channel through which fluid flows. Such designs attempt to offered little resistance to forward flow, require a designated cracking pressure to open and are simple to fabricate. In these design there is neither a suggestion nor use of a separate affixed flexible film device nor need for such a film device to close the pathway by means of pressurized backflow fluid. Such designs may find beneficial use for some low pressure medical applications.
Drew, U.S. Pat. No. 5,144,986 (1992), “One Way Flow Device” describes a class of simple film valves sometimes seen in novelties such as balloons. Drew teaches film devices where all ends and sides are attached to the sides of a fluid channel so as to allow only flow through a hole in a flexing film. The film has sufficient longitudinal movement so that when flow is in a forward direction it moves the hole to the channel center allowing forward fluid flow but when flow is reversed the film with the hole is pushed against a channel wall and effectively blocks passage of backflow fluid through the hole in the upstream direction. Due to the restrictive nature of the device hole as the only flow passage, clogging and poor seals are common with this design.
Koyanagi, U.S. Pat. No. 5,209,264 (1993), “Check Valve” is a flat film valve designed to vent air and outgases from sealed rice bags. A check flap under structured tension positions the flap normally closed to backflow. There is neither a recognized need for nor use of any control means for positioning a downstream edge of the check flap to seal off the backflow of ambient air. It is a problematic design that frequently fails to effectively prevent air backflow when the uncontrolled flap does not respond as hoped but remains open when the flap sticks to a wall or moves by chance in the wrong direction due to the absence of any edge control means.
Jang, U.S. Pat. No. 5,755,263 (1998), “Backward Flow Prevention Device” describes a variation of a duckbill design best described as a windsock duckbill. A truncated cone of flexible material is mounted on a pipe outlet, the pipe having side holes as fluid outlets. This windsock tube trails off downstream in the channel, guiding all flow from the outlet holes to the far end of the cone where it emerges back into the channel. When reverse backflow occurs the sock collapses, bunched up on itself and at off-angle to the pipe thereby preventing the backflow from entering the outlet holes. Such a construct is representative of several valve designs offering low friction loss expressed as flow resistance to forward movement but block reverse backflow fluid movement effectively if somewhat unpredictably.
Bennett, U.S. Pat. No. 5,881,772 (1999), “Smiling Duckbill Valve” is a curved lipped form of duckbill valves where tension compresses the walls of an elastomeric cylindrical valve body causing the lips to seal in a smile-like characterization reminiscent of ancient Greek play masks. There is no suggestion or use of any edge control means nor use of a non-tensioned film device in this design that effectively uses an internally structured spring to close the valve to backflow and imposes a significant threshold opening pressure head loss as well as an operational loss.
Persson, U.S. Pat. No. 6,810,914 (2004), “Method and Arrangement to Accomplish a One-Way Flow” describes a plastic bag deployed in a sewer pipe to prevent backflow while offering minimal interference to continuous sewage outflow. Noting that swinging iron gates and like devices impede flow and often result in disastrous blockage, a flexible elastic bag partially glued to the pipe wall is designed to flatten against the pipe wall during outflow thereby offering minimal resistance but deploys to open and fill with backflow fluid to temporarily block the sewer when reverse flow occurs. There is no suggestion or use of any edge control means nor use of a neutral tensioned film device, the bag having an inherent elasticity spring to maintain a normally closed aspect. It is doubtful the bag could survive the harsh conditions of sewer flow and sewage content, successfully deploy as contemplated, and avoid creating the very blockages it is designed to alleviate.
Chen, U.S. Pat. No. 7,201,273 (2007), “Air Packing Bag Having Film Type Check Valves” describes where two or more flexible films create fluid passages between the film layers which collapse and block off these passages when flow is reversed. Essentially the same mechanism described for the Jang windsock varying only in its use of flat film instead of a conical form. There is no recognition of a need for any edge control means or a descriptive use of a channel surface by a film device to enable fluid passage blockage.
Harper, U.S. Pat. No. 8,360,106 (2013), “Curved Pliant Film Valves” are a form of one-way valves where a pliant film device motivated by a compressible spring establishes a minimal resistant threshold pressure requirement to open a fluid channel to forward fluid movement and closes to prevent any reverse backflow of fluid through the same channel at any pressure. Curved pliant film (cpf) valves do not employ or recognize the need for any form of downstream edge control means, do employ a spring tension to control film device movement and do impose resistive threshold pressures to operate in forward flow mode. Cpf check valves are easily distinguished from biflex film valves as described herein by their use of springs to position their flexible film devices to prevent backflow. Cpf valves inherent use of threshold pressure to control forward pressure movement precludes their use in applications where film valves designs require little or no pressure resistance to open and operate.
None of these disclosures individually or in aggregate either describe, suggest or even recognize the need for a particularly low-cost, reliable, disposable, minimal component, securely sealing one-way valve action offering a design for effective film edge control that is easy to manufacture. The need for such a securely sealing one-way valve employing a pressure motivated film device with effective downstream edge control of reliable and of economical design has yet to be met.